My invention will be described hereinafter with reference to parking meters but it will be understood that that use is exemplary only.
At present almost all parking meters controlling the use of positions in automobile parking lots are coin-operated and mechanical in nature. In recent years there has been an increase in the cost of such parking to the point where quarter-dollars may be the only accepted coin and a spell of one or two hours of parking time may require the provision of many such coins. This presents an availability problem that is a growing source of inconvenience to frequent users of such meters. Attempts have been made therefore to devise credit card related systems to operate parking meters.
One approach is the use of a conventional bank credit card, or Visa or Mastercharge card, to purchase a magnetically encoded parking card entitling the purchaser to a number of units, for example 20 hours, of parking time (see for instance Kenyon UK Patent Application No. 2027965A). The parking card could be dispensed from a bank money dispensing machine or from an adjacent stand-alone dispensing machine after a standard bank credit card, or Visa or Mastercharge card, had been temporarily magnetically encoded to allow dispensing of the parking card. The parking card could then be carried in a purse or wallet and used in the parking location. However, provision would be required for reading the card's magnetic symbols, for selecting the required value and time of the parking and for subtracting the cash value expended from the purchased value of the card. Both the reading and the subtracting processes are difficult to achieve with low-cost low-power apparatus. Typically a card with magnetic symbols must be scanned by a reading head at a known speed and this entails problems of cost and reliability. Then subtraction logic must be performed and the card rewritten with the unused value remaining. This requires a complicated mechanism and an associated sophisticated electrical system. An example of such a system may be found in Pfost et al. U.S. Pat. No. 4,020,325.
Because of the high cost, such systems have not come into general use in connection with parking meters. It is conceivable that such a system might be set up as a single unit to supply parking time to a large array of individual parking meters, which would distribute the cost. It could dispose coin-like parking tokens that could then be used as substitutes for coins in regular parking meters. However, many street areas have parking meters in widely dispersed locations not conveniently serviced by a central token dispenser. The need therefore exists for a low-cost box unit that could be added to an existing parking meter post to provide parking time with the aid of a low cost card. The electrical power requirement of each box should be low enough to be provided by battery rather than 60 Hz electrical power line.
In the present state of the art of magnetically encoded cards, it is difficult to apply them economically to parking control. My invention makes use of capacitively encoded cards of special design to achieve parking control at considerably lower cost.
There have been a few descriptions of capacitivelyencoded cards, different from mine, in the literature of cards and card readers. For instance, Cuttill et al. U.S. Pat. No. 4,017,834, Apr. 12, 1977, discloses a credit card precoded in binary code representing several digits by an arrangement of high dielectric-constant spots or discs and low dielectric-constant spots or discs arranged in several bit groupings related to a plurality of identification digits.
Another system is disclosed in Eaton U.S. Pat. No. 4,328,415, May 4, 1982, in which a card for a viewdata terminal is read and used to enable access to the viewdata computer and to charge the appropriate account for use of the viewdata system. The card reader detects voltage signals from capacitive couplings between electrodes in the card.
In U.S. Pat. Nos. 4,017,834 and 4,328,415 the important function of the coding is that the card identifies the user of the card, in order to allow properly-billed credit or service charges.
In my invention to be described hereinafter the capacitive coding does not identify the user of the card but does represent prepaid services. The electronic readout system is significantly different and simpler than the readout systems in U.S. Pat. Nos. 4,017,834 and 4,328,415 since readout of digital bits is not needed.